Wire wrapping tool

ABSTRACT

A power driven tool for making a solderless connection between a wire and an electric terminal by wrapping the wire in successive convolutions about and in intimate engagement with the terminal. A wrapping bit of the tool is indexed to the proper point for quick easy insertion of the wire and operates positively and quickly for a complete wrapping cycle.

United States Patent 11 1 1111 3,903,936 Bergmann Sept. 9, 1975 [54] WIRE WRAPPING TOOL 3,243,130 3/1966 Rebechini et a1. 242 717 [76] Inventor: Adolph G. Bergmann, 8 Westwood La,, Bar i gto RI, 02806 Primary ExaminerLowell A. Larson F1 d M 8 1974 Attorney, Agent, or FirmBarlow & Barlow 1 e ay 47 ,5 7 [211 No 3 0 57 ABSTRACT 52 us. c1 140/124; 242/717 A 190W3r driven for making a Solderless Connec- 51 1m 01. B21F 15/04 between a Wife and an electric terminal by Wrap- [58] Field of sarch 1 40/1 19 122 124 l l ping the wire in successive convolutions about and in 7 intimate engagement with the terminal. A wrapping bit of the tool is indexed to the proper point for quick [56] References Cited easy insertion of the wire and operates positively and UNITED STATES PATENTS quickly for a complete wrapping cycle.

2,649,121 8/1953 Reck 140/124 10 Claims, 5 Drawing Figures WIRE WRAPPING TooL BACKGROUND OF THE INVENTION In many hand-held wire wrapping tools there is consumption of time in threading the wire into the tool because the bit does not index to the required location and must be hand manipulated prior to threading. There have been pneumatic and electric tools utilized and also indexing mechanisms as illustrated in US. Pat. No. 3,219,067. Such indexing mechanisms depend upon loading of a spring to reverse the rotation of the bit bringing it to a certain location by use of the loaded spring. This may unwrap the last turn of wire, is often uncertain, and springs may fatigue.

In US. Pat. No. 3,717,183 indexing is provided by a roller bearing on a spring-loaded trigger, the spring pressure of the trigger forcing back an indented cam with a lesser spring pressure, which cam is coupled to the drive shaft, the roller bearing rolling around as the cam continues to turn from inertial force until the bearing seats in the indent of the cam. This causes the trigger and operators finger to annoyingly bounce until the inertial force has stopped. This device also causes a high trigger pressure to be applied by the operator due to the engagement and higher pressure disengagement spring mechanisms.

Further, tests of prior devices have shown that tool weight, balance and trigger pressure in particular have an effect on the operators feel and quality of the wrapped connection. Too much pressure against the tool causes the turns of wire to overwrap one another and not enough pressure causes the turns of wire to be spaced too far apart to provide a satisfactory mechanically tight connection.

Assuming that the tool is light enough in weight and balanced properly, if the pressure to actuate the trigger is in the range of 16 ozs. and higher, the tendency is to press too hard against the turns of wire causing the above mentioned rejectable overwraps, especially on smaller gage wire such as 28 and 30 gage wire.

For this reason, most manufacturers sell what are called anti-backforce devices, a spring loaded device to be installed in their tool in back of the rotating bit for a particular wire gage. This allows the bit to recede rather than the wire to be overwrapped when the operator exerts too much pressure on the tool. Besides the additional cost of the device for each wire gage or two, almost complete disassembly of the tool is required to install the device.

Motors which operate a wire wrapping tool usually rotate about 13 thousand revolutions, per minute. Gearing then reduces this to about 4,500 revolutions per minute. Considerable inertia is developed at these speeds and if a positive stop is inserted for indexing, large stresses occur and breakage is frequent and trials have found this to be unseccessful and have rejected this type of operation.

SUMMARY OF THE INVENTION The concepts of this invention are not only to provide a drive and index mechanism which allows the tool to go from high speed to an abrupt stop at a fixed position repetitively within fi" without damage to the gear train or other parts of the tool, but also to provide a drive and index mechanism that does not require some part of the driving mechanism to be engaged and disengaged thereby causing a higher trigger pressure and the need for anti-backforce devices, As the speed of the cycle (r.p.m., index stop and loading) constitutes the number of connections per hour and hence the labor cost, the wire wrapping tool must go from full wrap speed to an index stop almost instantaneously.

The speed and weight of the driving shaft, motor shaft, rotating bit and any attachments thereto naturally build up a considerable inertial force as they are rotating, which then must be abruptly stopped. This abrupt stop can generate great harm and damage to the gear train and other components.

In carrying forth the concepts, the present invention comprises a housing with a pistol grip handle, and extending from the housing is a rotatable bit disposed in a tubular sleeve, the bit having a longitudinally extending bore in its forward end for the reception of a terminal post on which the wire is to be wrapped, and there is a radially offset longitudinal groove for the reception of the wire. In one version a permanent magnet electric motor having means to provide a dynamic brake, is disposed in the housing for driving the bit. A trigger operated switch controls the motor. The electric current drives the motor in one direction by closing this switch and when the trigger is released, the motor is shorted so that it acts as a generator driven by the inertia of the bit and its driving mechanism, providing the power for this generator and thus a braking action occurs to bring the motor to a stop. Some abutment is provided so that when the trigger is released, the trigger will be in the path of this abutment to be engaged and thus index or locate the bit in a desired position. When such a stop is engaged the bit will maintain a position against the stop and not bound back or move in the opposite direction to position the bit out of line. After the abutment is engaged, a clutch permits further rotation of the motor and driving gears until the driving inertia is expended, thus relieving strain on the driving gears.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a half section of the casing showing some of the driving parts in section;

FIG. 2 is a sectional view through the trigger stop on line 2--2;

FIG. 3 is an enlarged end view of the bit and sleeve;

FIG. 4 is a view illustrating the electrical circuit for the motor; and

FIG. 5 is a view similar to FIG. 1 showing a modification of the drive.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring particularly to FIG. 1 a housing designated generally 10 has a pistol grip portion 11 shaped as illustrated in the drawing. A motor 14 having a dynamic brake has secured to its opposite ends at 15 and 16 elastomeric members of a diameter a little greater than the diameter of the motor 14 so as to space the motor from the side walls of the circular type casing which embraces the motor. Stops at 17 and 18 molded in the casing engage the ends of the elastomeric members 15 and 16 so as to prevent the motor from axial or radial movement in the casing. The motor is the heaviest part of the instrument and if dropped places a strain on the parts of the casing which mount it, but by use of the elastomeric members engaging the casing at spaced points and the stops which are molded into the casing, the load from such dropping is distributed over the easing and will withstand much greater forces than molding into the casing some fins upon which such strains occur.

The armature shaft of the motor is fitted with a gear which engages gear 21 on drive shaft 22, which shaft has a stud portion 23 which engages a bearing formed in the elastomeric member 16. An annual part of a collet 25 is secured in the end of the casing 10 and provides a bearing at 26 for a coupling 27 which is recessed as at 28 and provided with a flat surface 29 that engages a similar flat surface 30 on the bit 31 which is elongated as at 32 to extend through a sleeve 33 which sleeve is clamped by nut 34 on the collet 25 so as to cause it to remain fixed with relation to the casing as the bit 31 is driven. This sleeve 33 is notched as at 35 and 36 (FIG. 3) and is expanded as at 37 so as to provide an entrance mouth for a wire to be passed into the groove 38 in the bit 32. Then this wire may be bent outwardly into one of the notches 35 or 36 while the pin or post upon which the wire is to be wrapped is inserted in the hole 39 in the bit. 7

The gear 21 from which a hub 40 extends with a disc 41 secured to the hub comprises a unit which is free to rotate on a shaft 22 and is driven by the gear 20 on the armature shaft. This unit is limited in its movement axially of shaft 22 by a stop 24, such as a snap ring. A disc 42 is keyed to the shaft 22 to axially slide thereon and rotate therewith, and it has a face, which may be polyurethane, to engage the face of the disc 41 so that when pressed into engagement with the disc 41 by the spring 43, the shaft 22 will be driven. Spring 43 is precalculated to supply pressure against disc 42 to cause sufficient friction between the faces of discs 41 and 42 for driving one from the other. A driving friction is between the disc faces and not between spring 43 and disc 42 or spring 43 and collar 47. Disc 42 is keyed to shaft 22 to prevent relative circular movement of disc 42. This also permits the use of a lower spring pressure as the surface area of the two disc faces is greater than the surface area of spring 43 and disc 42 or spring 43 and shoulder 47 and if disc 42 were not keyed slippage could take place other than between the disc faces.

A mechanical stop such as collar 47 is applied to shaft 22. This collar may be axially adjusted along shaft 22 and held by set screw 47. The distance of this me chanical stop 47 from the other end of disc 42 determines the compressed length of spring 43 and the pressure exerted, which in turn creates the friction between the disc faces. This pressure is precalculated so as to provide rotating bit 31 with sufficient torque to wrap the heaviest gage wire required.

As it is advantageous for one tool to be able to wrap US 20 gage thru US 30 gage wire, tests were run to determine that 20 gage wire requires approximately 2- inch lbs. of torque from the rotating bit 31 and spring pressures (compressed length) were determined so as to provide that amount of torque. If a tool were only to be used for US 30 gage wrapping, a lesser torque would be required and hence lower spring pressure and friction. Therefore, the compressed length of spring 43 (if the same load rate spring were used) would be lessened by lengthening the distance between mechanical stop 47 and the disc 42 or a spring of lesser load rate could be used.

Of considerable importance is that mechanical stop 47 and retaining ring 24 in FIG. 1 restrain all spring pressure between them so that no pressure is exerted axially on bearing surface 26 or 23 in FIG. 1, as axial pressure on bearing or other surfaces can reduce torque output of a tool and cause premature bearing surface wear, the index and drive mechanism described above eliminates such condition and requires only motor power sufficient to achieve the desired torque.

Also secured to the shaft 22 is a cam 44 which is notched to provide an abutment 45 for the reception of the portion 50 of the trigger 48. The notch 51 extends into the surface of the cam so that there is also provided an abutment 46 of lesser extent to prevent any rebound when the abutment 45 engages the abutment 50 of the trigger 48. A trigger 48 as shown in FIG. 1 is pivoted as at 49 and has a portion 50 to extend into the path of abutment 45 when it is rotating and when the trigger is in its released position. The trigger is moved to its release position by spring means within switch 57 which is transmitted to the trigger by a leaf 52 and roller 53. Auxiliary spring means may be provided as necessary. Notch 51 in cam 44 is in radial relationship to tang driver 29 housed in bearing or nose piece 27 so as to position rotating bit 31 in the desired position, usually l2 oclock when the tool is held in an upright posi-.

tion. When the motor 14 is energized, the motor shaft, drive shaft and all attachments thereto rotate at the speeds described. The inertial force now becomes greater than the set torque force and when the front area 50 of trigger 48 contacts high abutment 45 of cam 44, it stops disc 42, shaft 22 and rotating bit 31 in the desired position, however, gears 20 and 21 and cou pling and/or disc 41 keep on rotating until the inertial force has subsided to a force equal to or less than the torque force. In this manner, no strain greater than the gears were designed for is ever imparted to them by the abrupt stop of the high inertial force.

Referring now to FIG. 4 the source of power is designated 55 and 56 and single-pole double-throw switch 57, when on terminal 58, will drive the motor 14 in the direction to rotate the bit. However, when in released position, the switch 57 contacts terminal 59 so as to in effect short the motor 14, disconnecting the drive of the motor and thus the inertia of the motor and the parts connected thereto cause the motor to act as a generator or in other words exert a braking action on r the motor to cause its armature shaft to come to a stop. This movement of the switch arm 57 to contact 59 is caused when the trigger 48 is released and as this trigger 48' is released the portion 50 of the trigger moves into the path of the abutment 45 to stop the bit to which this stop is connected at the desired location for a threading of another wire into the tool.

In FIG. 5 a direct drive from the motor is shown. The motor 14 is equipped with a cluster type gear head with a drive shaft 20' extending therefrom. A coupling 21 has a disc 41' which is fixed to the shaft 20 to be rotated thereby but is freely rotatable on shaft 22' which extends through the disc 41. A stop 24' limits axial movement of the disc 41on shaft 22. Shaft 22' has keyed thereon disc 42 which is axially slidable on shaft 22' and urged into face-to-face contact with disc 41' by spring 43' in the manner described with reference to FIG. 1 and the operation is otherwise the same as the showing in FIG. 1.

The mechanisms above described are electrically driven, however, an air driven motor may be used in which a spring loaded air valve may be manipulated by the trigger 48 in place of the control 57 shown in FIG.

1 as, for example, as disclosed in US. Pat. No. 3,318,344. In either case, the clutch mechanism operates the same.

I claim:

1. A wire wrapping tool comprising 1. a rotary bit 2. a motor j 3. a friction clutch having two faces slidably and continuously in engagement through whichsaid motor drives said bit 4. indexing means operably connected to said bit and having an angular index position related to an angular position of said bit,

5. control means for said motor which in one position energizes the motor and in another position operates said indexing means.

2. A wire wrapping tool as in claim 1 wherein said clutch is face to face frictional engagement with means to adjust the frictional force.

3. A wire wrapping tool as in claim 2 wherein one clutch face is coupled to the motor and the other face is coupled to the bit, and the friction is adjustable so that when the indexing means operates to stop the one clutch face and the bit, the other of the clutch faces and the motor may continue to rotate until the inertia of the parts is spent.

4. A wire wrapping tool as in claim 3 wherein said motor is electrical and dynamic braking means for said motor is present.

5. A wire wrapping tool as in claim 1 wherein said clutch comprising a face to face friction relation of two members with one member having a part in axial sliding relation with a part of the other member, said sliding relation being limited by a pair of stop means and means acting between said stop means to urge said friction faces against one of said stop means, said one stop being on the driven side of said clutch whereby no axial thrust is imparted to the drive side of said clutch.

6. A wire wrapping tool comprising 1. an electric motor, 2. dynamic braking means for said motor, 3. a rotary bit, 4. means for driving the rotary bit from said motor, 5. indexing means operably connected to said bit,

said indexing means having an angular index position related to an angular position of the bit,- 6. control means for said motor including said dynamic braking means which in one position energizes said motor and in a second position deenergizes the motor and connects said dynamic braking means and operates said indexing means. 7. A wire wrapping tool as in claim 6 wherein 7. said indexing means comprises a stop, and

8. said control means includes a member to engage said stop when in de-energizing position.

8. A wire wrapping tool as in claim 6 wherein 7. said indexing means comprising a stop, and

8. said control means includes a member to engage said stop when in de-energizing position whereby when said stop is engaged by said member it is held in a desired indexing position.

9. A wire wrapping tool as in claim 6 wherein there is a casing about said motor, and elastomeric members in spaced relation support said motor in said casing to distribute an impact load therealong.

10. A wire wrapping tool as in claim 6 wherein there is a casing about said motor, elastomeric members in spaced relation support said motor in said casing to distribute an impact load therealong, abutment means carried by said casing engaging said elastomeric members to limit movement of said motor. 

1. A wire wrapping tool comprising
 1. a rotary bit
 2. a motor
 3. a friction clutch having two faces slidably and continuously in engagement through which said motor drives said bit
 4. indexing means operably connected to said bit and having an angular index position related to an angular position of said bit
 5. control means for said motor which in one position energizes the motor and in another position operates said indexing means.
 2. a motor
 2. A wire wrapping tool as in claim 1 wherein said clutch is face to face frictional engagement with means to adjust the frictional force.
 2. dynamic braking means for said motor,
 3. a rotary bit,
 3. A wire wrapping tool as in claim 2 wherein one clutch face is coupled to the motor and the other face is coupled to the bit, and the friction is adjustable so that when the indexing means operates to stop the one clutch face and the bit, the other of the clutch faces and the motor may continue to rotate until the inertia of the parts is spent.
 3. a friction clutch having two faces slidably and continuously in engagement through which said motor drives said bit
 4. indexing means operably connected to said bit and having an angular index position related to an angular position of said bit
 4. A wire wrapping tool as in claim 3 wherein said motor is electrical and dynamic braking means for said motor is present.
 4. means for driving the rotary bit from said motor,
 5. A wire wrapping tool as in claim 1 wherein said clutch comprising a fAce to face friction relation of two members with one member having a part in axial sliding relation with a part of the other member, said sliding relation being limited by a pair of stop means and means acting between said stop means to urge said friction faces against one of said stop means, said one stop being on the driven side of said clutch whereby no axial thrust is imparted to the drive side of said clutch.
 5. control means for said motor which in one position energizes the motor and in another position operates said indexing means.
 5. indexing means operably connected to said bit, said indexing means having an angular index position related to an angular position of the bit,
 6. control means for said motor including said dynamic braking means which in one position energizes said motor and in a second position de-energizes the motor and connects said dynamic braking means and operates said indexing means.
 6. A wire wrapping tool comprising
 7. said indexing means comprises a stop, and
 7. A wire wrapping tool as in claim 6 wherein
 7. said indexing means comprising a stop, and
 8. A wire wrapping tool as in claim 6 wherein
 8. said control means includes a member to engage said stop when in de-energizing position.
 8. said control means includes a member to engage said stop when in de-energizing position whereby when said stop is engaged by said member it is held in a desired indexing position.
 9. A wire wrapping tool as in claim 6 wherein there is a casing about said motor, and elastomeric members in spaced relation support said motor in said casing to distribute an impact load therealong.
 10. A wire wrapping tool as in claim 6 wherein there is a casing about said motor, elastomeric members in spaced relation support said motor in said casing to distribute an impact load therealong, abutment means carried by said casing engaging said elastomeric members to limit movement of said motor. 